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Nipun TS, Khatib A, Ahmed QU, Nasir MHM, Supandi F, Taher M, Saiman MZ. Preliminary Phytochemical Screening, In Vitro Antidiabetic, Antioxidant Activities, and Toxicity of Leaf Extracts of Psychotria malayana Jack. PLANTS 2021; 10:plants10122688. [PMID: 34961160 PMCID: PMC8707723 DOI: 10.3390/plants10122688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 12/04/2022]
Abstract
Psychotria malayana Jack belongs to the Rubiacea and is widespread in Southeast Asian countries. It is traditionally used to treat diabetes. Despite its potential medicinal use, scientific proof of this pharmacological action and the toxic effect of this plant are still lacking. Hence, this study aimed to investigate the in vitro antidiabetic and antioxidant activities, toxicity, and preliminary phytochemical screening of P. malayana leaf extracts by gas chromatography-mass spectrometry (GC-MS) after derivatization. The antidiabetic activities of different extracts of this plant were investigated through alpha-glucosidase inhibitory (AGI) and 2-NBDG glucose uptake using 3T3-L1 cell line assays, while the antioxidant activity was evaluated using DPPH and FRAP assays. Its toxicological effect was investigated using the zebrafish embryo/larvae (Danio rerio) model. The mortality, hatchability, tail-detachment, yolk size, eye size, beat per minute (BPM), and body length were taken into account to observe the teratogenicity in all zebrafish embryos exposed to methanol extract. The LC50 was determined using probit analysis. The methanol extract showed the AGI activity (IC50 = 2.71 ± 0.11 μg/mL), insulin-sensitizing activity (at a concentration of 5 µg/mL), and potent antioxidant activities (IC50 = 10.85 μg/mL and 72.53 mg AAE/g for DPPH and FRAP activity, respectively). Similarly, the water extract exhibited AGI activity (IC50 = 6.75 μg/mL), insulin-sensitizing activity at the concentration of 10 μg/mL, and antioxidant activities (IC50 = 27.12 and 33.71 μg/mL for DPPH and FRAP activity, respectively). The methanol and water extracts exhibited the LC50 value higher than their therapeutic concentration, i.e., 37.50 and 252.45 µg/mL, respectively. These results indicate that both water and methanol extracts are safe and potentially an antidiabetic agent, but the former is preferable since its therapeutic index (LC50/therapeutic concentration) is much higher than for methanol extracts. Analysis using GC-MS on derivatized methanol and water extracts of P. malayana leaves detected partial information on some constituents including palmitic acid, 1,3,5-benzenetriol, 1-monopalmitin, beta-tocopherol, 24-epicampesterol, alpha-tocopherol, and stigmast-5-ene, that could be a potential target to further investigate the antidiabetic properties of the plant. Nevertheless, isolation and identification of the bioactive compounds are required to confirm their antidiabetic activity and toxicity.
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Affiliation(s)
- Tanzina Sharmin Nipun
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Pahang Darul Makmur, Malaysia; (T.S.N.); (Q.U.A.); (M.T.)
- Department of Pharmacy, Faculty of Biological Sciences, University of Chittagong, Chittagong 4331, Bangladesh
| | - Alfi Khatib
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Pahang Darul Makmur, Malaysia; (T.S.N.); (Q.U.A.); (M.T.)
- Faculty of Pharmacy, Airlangga University, Surabaya 60155, Indonesia
- Correspondence: (A.K.); (M.Z.S.)
| | - Qamar Uddin Ahmed
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Pahang Darul Makmur, Malaysia; (T.S.N.); (Q.U.A.); (M.T.)
| | - Mohd Hamzah Mohd Nasir
- Central Research and Animal Facility, Kulliyyah of Science, International Islamic University Malaysia, Kuantan 25200, Pahang Darul Makmur, Malaysia;
| | - Farahaniza Supandi
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia;
| | - Muhammad Taher
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Pahang Darul Makmur, Malaysia; (T.S.N.); (Q.U.A.); (M.T.)
| | - Mohd Zuwairi Saiman
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia;
- Centre for Research in Biotechnology for Agriculture (CEBAR), University of Malaya, Kuala Lumpur 50603, Malaysia
- Centre for Natural Products Research and Drug Discovery (CENAR), University of Malaya, Kuala Lumpur 50603, Malaysia
- Correspondence: (A.K.); (M.Z.S.)
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Thant MT, Sritularak B, Chatsumpun N, Mekboonsonglarp W, Punpreuk Y, Likhitwitayawuid K. Three Novel Biphenanthrene Derivatives and a New Phenylpropanoid Ester from Aerides multiflora and Their α-Glucosidase Inhibitory Activity. PLANTS (BASEL, SWITZERLAND) 2021; 10:385. [PMID: 33671404 PMCID: PMC7922108 DOI: 10.3390/plants10020385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 11/18/2022]
Abstract
A phytochemical investigation on the whole plants of Aerides multiflora revealed the presence of three new biphenanthrene derivatives named aerimultins A-C (1-3) and a new natural phenylpropanoid ester dihydrosinapyl dihydroferulate (4), together with six known compounds (5-10). The structures of the new compounds were elucidated by analysis of their spectroscopic data. All of the isolates were evaluated for their α-glucosidase inhibitory activity. Aerimultin C (3) showed the most potent activity. The other compounds, except for compound 4, also exhibited stronger activity than the positive control acarbose. Compound 3 showed non-competitive inhibition of the enzyme as determined from a Lineweaver-Burk plot. This study is the first phytochemical and biological investigation of A. multiflora.
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Affiliation(s)
- May Thazin Thant
- Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand; (M.T.T.); (K.L.)
- Department of Pharmacognosy, University of Pharmacy, Yangon 11031, Myanmar
| | - Boonchoo Sritularak
- Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand; (M.T.T.); (K.L.)
- Natural Products for Ageing and Chronic Diseases Research Unit, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Nutputsorn Chatsumpun
- Department of Pharmacognosy, Faculty of Pharmacy, Mahidol University, Bangkok 10400, Thailand;
| | - Wanwimon Mekboonsonglarp
- Scientific and Technological Research Equipment Centre, Chulalongkorn University, Bangkok 10330, Thailand;
| | - Yanyong Punpreuk
- Department of Agriculture, Kasetsart University, Bangkok 10900, Thailand;
| | - Kittisak Likhitwitayawuid
- Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand; (M.T.T.); (K.L.)
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Nipun TS, Khatib A, Ibrahim Z, Ahmed QU, Redzwan IE, Saiman MZ, Supandi F, Primaharinastiti R, El-Seedi HR. Characterization of α-Glucosidase Inhibitors from Psychotria malayana Jack Leaves Extract Using LC-MS-Based Multivariate Data Analysis and In-Silico Molecular Docking. Molecules 2020; 25:molecules25245885. [PMID: 33322801 PMCID: PMC7763559 DOI: 10.3390/molecules25245885] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/07/2020] [Accepted: 12/10/2020] [Indexed: 01/15/2023] Open
Abstract
Psychotria malayana Jack has traditionally been used to treat diabetes. Despite its potential, the scientific proof in relation to this plant is still lacking. Thus, the present study aimed to investigate the α-glucosidase inhibitors in P.malayana leaf extracts using a metabolomics approach and to elucidate the ligand–protein interactions through in silico techniques. The plant leaves were extracted with methanol and water at five various ratios (100, 75, 50, 25 and 0% v/v; water–methanol). Each extract was tested for α-glucosidase inhibition, followed by analysis using liquid chromatography tandem to mass spectrometry. The data were further subjected to multivariate data analysis by means of an orthogonal partial least square in order to correlate the chemical profile and the bioactivity. The loading plots revealed that the m/z signals correspond to the activity of α-glucosidase inhibitors, which led to the identification of three putative bioactive compounds, namely 5′-hydroxymethyl-1′-(1, 2, 3, 9-tetrahydro-pyrrolo (2, 1-b) quinazolin-1-yl)-heptan-1′-one (1), α-terpinyl-β-glucoside (2), and machaeridiol-A (3). Molecular docking of the identified inhibitors was performed using Auto Dock Vina software against the crystal structure of Saccharomyces cerevisiae isomaltase (Protein Data Bank code: 3A4A). Four hydrogen bonds were detected in the docked complex, involving several residues, namely ASP352, ARG213, ARG442, GLU277, GLN279, HIE280, and GLU411. Compound 1, 2, and 3 showed binding affinity values of −8.3, −7.6, and −10.0 kcal/mol, respectively, which indicate the good binding ability of the compounds towards the enzyme when compared to that of quercetin, a known α-glucosidase inhibitor. The three identified compounds that showed potential binding affinity towards the enzymatic protein in molecular docking interactions could be the bioactive compounds associated with the traditional use of this plant.
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Affiliation(s)
- Tanzina Sharmin Nipun
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Malaysia; (T.S.N.); (Z.I.); (Q.U.A.); (I.E.R.)
- Department of Pharmacy, Faculty of Biological Sciences, University of Chittagong, Chittagong 4331, Bangladesh
| | - Alfi Khatib
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Malaysia; (T.S.N.); (Z.I.); (Q.U.A.); (I.E.R.)
- Faculty of Pharmacy, Airlangga University, Surabaya 60155, Indonesia;
- Correspondence: (A.K.); (M.Z.S.)
| | - Zalikha Ibrahim
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Malaysia; (T.S.N.); (Z.I.); (Q.U.A.); (I.E.R.)
| | - Qamar Uddin Ahmed
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Malaysia; (T.S.N.); (Z.I.); (Q.U.A.); (I.E.R.)
| | - Irna Elina Redzwan
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Malaysia; (T.S.N.); (Z.I.); (Q.U.A.); (I.E.R.)
| | - Mohd Zuwairi Saiman
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia;
- Center for Research in Biotechnology for Agriculture (CEBAR), Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia
- Correspondence: (A.K.); (M.Z.S.)
| | - Farahaniza Supandi
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia;
| | | | - Hesham R. El-Seedi
- Pharmacognosy Group, Department of Pharmaceutical Biosciences, BMC, Uppsala University, SE-751 23 Uppsala, Sweden;
- International Research Center for Food Nutrition and Safety, Jiangsu University, Zhenjiang 212013, China
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Okuyama M, Miyamoto M, Matsuo I, Iwamoto S, Serizawa R, Tanuma M, Ma M, Klahan P, Kumagai Y, Tagami T, Kimura A. Substrate recognition of the catalytic α-subunit of glucosidase II from Schizosaccharomyces pombe. Biosci Biotechnol Biochem 2017; 81:1503-1511. [DOI: 10.1080/09168451.2017.1320520] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Abstract
The recombinant catalytic α-subunit of N-glycan processing glucosidase II from Schizosaccharomyces pombe (SpGIIα) was produced in Escherichia coli. The recombinant SpGIIα exhibited quite low stability, with a reduction in activity to <40% after 2-days preservation at 4 °C, but the presence of 10% (v/v) glycerol prevented this loss of activity. SpGIIα, a member of the glycoside hydrolase family 31 (GH31), displayed the typical substrate specificity of GH31 α-glucosidases. The enzyme hydrolyzed not only α-(1→3)- but also α-(1→2)-, α-(1→4)-, and α-(1→6)-glucosidic linkages, and p-nitrophenyl α-glucoside. SpGIIα displayed most catalytic properties of glucosidase II. Hydrolytic activity of the terminal α-glucosidic residue of Glc2Man3-Dansyl was faster than that of Glc1Man3-Dansyl. This catalytic α-subunit also removed terminal glucose residues from native N-glycans (Glc2Man9GlcNAc2 and Glc1Man9GlcNAc2) although the activity was low.
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Affiliation(s)
- Masayuki Okuyama
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Masashi Miyamoto
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Ichiro Matsuo
- Graduate School of Science and Technology, Gunma University, Kiryu, Japan
| | - Shogo Iwamoto
- Graduate School of Science and Technology, Gunma University, Kiryu, Japan
| | - Ryo Serizawa
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Masanari Tanuma
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Min Ma
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Patcharapa Klahan
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Yuya Kumagai
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Takayoshi Tagami
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Atsuo Kimura
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
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Feasley CL, van der Wel H, West CM. Evolutionary diversity of social amoebae N-glycomes may support interspecific autonomy. Glycoconj J 2015; 32:345-59. [PMID: 25987342 DOI: 10.1007/s10719-015-9592-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 04/11/2015] [Accepted: 04/14/2015] [Indexed: 10/23/2022]
Abstract
Multiple species of cellular slime mold (CSM) amoebae share overlapping subterranean environments near the soil surface. Despite similar life-styles, individual species form independent starvation-induced fruiting bodies whose spores can renew the life cycle. N-glycans associated with the cell surface glycocalyx have been predicted to contribute to interspecific avoidance, resistance to pathogens, and prey preference. N-glycans from five CSM species that diverged 300-600 million years ago and whose genomes have been sequenced were fractionated into neutral and acidic pools and profiled by MALDI-TOF-MS. Glycan structure models were refined using linkage specific antibodies, exoglycosidase digestions, MALDI-MS/MS, and chromatographic studies. Amoebae of the type species Dictyostelium discoideum express modestly trimmed high mannose N-glycans variably modified with core α3-linked Fuc and peripherally decorated with 0-2 residues each of β-GlcNAc, Fuc, methylphosphate and/or sulfate, as reported previously. Comparative analyses of D. purpureum, D. fasciculatum, Polysphondylium pallidum, and Actyostelium subglobosum revealed that each displays a distinctive spectrum of high-mannose species with quantitative variations in the extent of these modifications, and qualitative differences including retention of Glc, mannose methylation, and absence of a peripheral GlcNAc, fucosylation, or sulfation. Starvation-induced development modifies the pattern in all species but, except for universally observed increased mannose-trimming, the N-glycans do not converge to a common profile. Correlations with glycogene repertoires will enable future reverse genetic studies to eliminate N-glycomic differences to test their functions in interspecific relations and pathogen evasion.
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Affiliation(s)
- Christa L Feasley
- Department of Biochemistry & Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, 975 NE 10th St., BRC-415, OUHSC, Oklahoma City, OK, 73104, USA,
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6
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Crystal structure and substrate-binding mode of GH63 mannosylglycerate hydrolase from Thermus thermophilus HB8. J Struct Biol 2015; 190:21-30. [DOI: 10.1016/j.jsb.2015.02.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 11/20/2022]
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Shibuya A, Margulis N, Christiano R, Walther TC, Barlowe C. The Erv41-Erv46 complex serves as a retrograde receptor to retrieve escaped ER proteins. ACTA ACUST UNITED AC 2015; 208:197-209. [PMID: 25583996 PMCID: PMC4298680 DOI: 10.1083/jcb.201408024] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signal-dependent sorting of proteins in the early secretory pathway is required for dynamic retention of endoplasmic reticulum (ER) and Golgi components. In this study, we identify the Erv41-Erv46 complex as a new retrograde receptor for retrieval of non-HDEL-bearing ER resident proteins. In cells lacking Erv41-Erv46 function, the ER enzyme glucosidase I (Gls1) was mislocalized and degraded in the vacuole. Biochemical experiments demonstrated that the luminal domain of Gls1 bound to the Erv41-Erv46 complex in a pH-dependent manner. Moreover, in vivo disturbance of the pH gradient across membranes by bafilomycin A1 treatment caused Gls1 mislocalization. Whole cell proteomic analyses of deletion strains using stable isotope labeling by amino acids in culture identified other ER resident proteins that depended on the Erv41-Erv46 complex for efficient localization. Our results support a model in which pH-dependent receptor binding of specific cargo by the Erv41-Erv46 complex in Golgi compartments identifies escaped ER resident proteins for retrieval to the ER in coat protein complex I-formed transport carriers.
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Affiliation(s)
- Aya Shibuya
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Neil Margulis
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Romain Christiano
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Tobias C Walther
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Charles Barlowe
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
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Miyazaki T, Ichikawa M, Yokoi G, Kitaoka M, Mori H, Kitano Y, Nishikawa A, Tonozuka T. Structure of a bacterial glycoside hydrolase family 63 enzyme in complex with its glycosynthase product, and insights into the substrate specificity. FEBS J 2013; 280:4560-71. [DOI: 10.1111/febs.12424] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 06/28/2013] [Accepted: 07/01/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Takatsugu Miyazaki
- Department of Applied Biological Science; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Megumi Ichikawa
- Department of Applied Biological Science; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Gaku Yokoi
- Department of Applied Biological Science; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Motomitsu Kitaoka
- National Food Research Institute; National Agriculture and Food Research Organization; Tsukuba Ibaraki Japan
| | - Haruhide Mori
- Research Faculty of Agriculture; Hokkaido University; Kita-ku Sapporo Japan
| | - Yoshikazu Kitano
- Department of Applied Biological Science; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Atsushi Nishikawa
- Department of Applied Biological Science; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Takashi Tonozuka
- Department of Applied Biological Science; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
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Barker MK, Rose DR. Specificity of Processing α-glucosidase I is guided by the substrate conformation: crystallographic and in silico studies. J Biol Chem 2013; 288:13563-74. [PMID: 23536181 DOI: 10.1074/jbc.m113.460436] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The enzyme “GluI” is key to the synthesis of critical glycoproteins in the cell. RESULTS We have determined the structure of GluI, and modeled binding with its unique sugar substrate. CONCLUSION The specificity of this interaction derives from a unique conformation of the substrate. SIGNIFICANCE Understanding the mechanism of the enzyme is of basic importance and relevant to potential development of antiviral inhibitors. Processing α-glucosidase I (GluI) is a key member of the eukaryotic N-glycosylation processing pathway, selectively catalyzing the first glycoprotein trimming step in the endoplasmic reticulum. Inhibition of GluI activity impacts the infectivity of enveloped viruses; however, despite interest in this protein from a structural, enzymatic, and therapeutic standpoint, little is known about its structure and enzymatic mechanism in catalysis of the unique glycan substrate Glc3Man9GlcNAc2. The first structural model of eukaryotic GluI is here presented at 2-Å resolution. Two catalytic residues are proposed, mutations of which result in catalytically inactive, properly folded protein. Using Autodocking methods with the known substrate and inhibitors as ligands, including a novel inhibitor characterized in this work, the active site of GluI was mapped. From these results, a model of substrate binding has been formulated, which is most likely conserved in mammalian GluI.
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Affiliation(s)
- Megan K Barker
- Department of Medical Biophysics, University of Toronto, Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario M5G 2M9, Canada.
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Iino K, Iwamoto S, Kasahara Y, Matsuda K, Tonozuka T, Nishikawa A, Ito Y, Matsuo I. Facile construction of 1,2-cis glucosidic linkage using sequential oxidation–reduction route for synthesis of an ER processing α-glucosidase I substrate. Tetrahedron Lett 2012. [DOI: 10.1016/j.tetlet.2012.06.061] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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11
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Robledo-Ortiz CI, Flores-Carreón A, Hernández-Cervantes A, Álvarez-Vargas A, Lee KK, Díaz-Jiménez DF, Munro CA, Cano-Canchola C, Mora-Montes HM. Isolation and functional characterization of Sporothrix schenckii ROT2, the encoding gene for the endoplasmic reticulum glucosidase II. Fungal Biol 2012; 116:910-8. [DOI: 10.1016/j.funbio.2012.06.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 06/06/2012] [Accepted: 06/15/2012] [Indexed: 12/20/2022]
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12
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Miyazaki T, Matsumoto Y, Matsuda K, Kurakata Y, Matsuo I, Ito Y, Nishikawa A, Tonozuka T. Heterologous expression and characterization of processing α-glucosidase I from Aspergillus brasiliensis ATCC 9642. Glycoconj J 2011; 28:563-71. [PMID: 22020441 DOI: 10.1007/s10719-011-9356-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/06/2011] [Accepted: 10/06/2011] [Indexed: 01/12/2023]
Abstract
A gene for processing α-glucosidase I from a filamentous fungus, Aspergillus brasiliensis (formerly called Aspergillus niger) ATCC 9642 was cloned and fused to a glutathione S-transferase tag. The active construct with the highest production level was a truncation mutant deleting the first 16 residues of the hydrophobic N-terminal domain. This fusion enzyme hydrolyzed pyridylaminated (PA-) oligosaccharides Glc(3)Man(9)GlcNAc(2)-PA and Glc(3)Man(4)-PA and the products were identified as Glc(2)Man(9)GlcNAc(2)-PA and Glc(2)Man(4)-PA, respectively. Saturation curves were obtained for both Glc(3)Man(9)GlcNAc(2)-PA and Glc(3)Man(4)-PA, and the K (m) values for both substrates were estimated in the micromolar range. When 1 μM Glc(3)Man(4)-PA was used as a substrate, the inhibitors kojibiose and 1-deoxynojirimycin had similar effects on the enzyme; at 20 μM concentration, both inhibitors reduced activity by 50%.
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Affiliation(s)
- Takatsugu Miyazaki
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
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Purification and partial biochemical characterization of a membrane-bound type II-like α-glucosidase from the yeast morphotype of Sporothrix schenckii. Antonie van Leeuwenhoek 2011; 101:313-22. [DOI: 10.1007/s10482-011-9636-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 08/22/2011] [Indexed: 01/13/2023]
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14
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Barker MK, Wilkinson BL, Faridmoayer A, Scaman CH, Fairbanks AJ, Rose DR. Production and crystallization of processing α-glucosidase I: Pichia pastoris expression and a two-step purification toward structural determination. Protein Expr Purif 2011; 79:96-101. [PMID: 21640829 DOI: 10.1016/j.pep.2011.05.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 05/19/2011] [Accepted: 05/20/2011] [Indexed: 12/17/2022]
Abstract
Eukaryotic N-glycoprotein processing in the endoplasmic reticulum begins with the catalytic action of processing α-glucosidase I (αGlu). αGlu trims the terminal glucose from nascent glycoproteins in an inverting-mechanism glycoside hydrolysis reaction. αGlu has been studied in terms of kinetic parameters and potential key residues; however, the active site is unknown. A structural model would yield important insights into the reaction mechanism. A model would also be useful in developing specific therapeutics, as αGlu is a viable drug target against viruses with glycosylated envelope proteins. However, due to lack of a high-yielding overexpression and purification scheme, no eukaryotic structural model of αGlu has been determined. To address this issue, we overexpressed the Saccharomyces cerevisiae soluble αGlu, Cwht1p, in the host Pichia pastoris. It was purified in a simple two-step protocol, with a final yield of 4.2mg Cwht1p per liter of growth culture. To test catalytic activity, we developed a modified synthesis of a tetrasaccharide substrate, Glc(3)ManOMe. Cwht1p with Glc(3)ManOMe shows a K(m) of 1.26 mM. Cwht1p crystals were grown and subjected to X-ray irradiation, giving a complete diffraction dataset to 2.04 Å resolution. Work is ongoing to obtain phases so that we may further understand this fundamental member of the N-glycosylation pathway through the discovery of its molecular structure.
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Affiliation(s)
- Megan K Barker
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
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15
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Tonozuka T, Miyazaki T, Nishikawa A. Structural Similarity between a Starch-hydrolyzing Enzyme and an N-Glycan-Hydrolyzing Enzyme: Exohydrolases Cleaving α-1,X-Glucosidic Linkages to Produce β-Glucose. TRENDS GLYCOSCI GLYC 2011. [DOI: 10.4052/tigg.23.93] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Odaci D, Telefoncu A, Timur S. Maltose biosensing based on co-immobilization of α-glucosidase and pyranose oxidase. Bioelectrochemistry 2010; 79:108-13. [DOI: 10.1016/j.bioelechem.2009.12.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 12/12/2009] [Accepted: 12/24/2009] [Indexed: 10/20/2022]
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17
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Frade-Pérez MD, Hernández-Cervantes A, Flores-Carreón A, Mora-Montes HM. Biochemical characterization of Candida albicans α-glucosidase I heterologously expressed in Escherichia coli. Antonie Van Leeuwenhoek 2010; 98:291-8. [DOI: 10.1007/s10482-010-9437-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Accepted: 03/23/2010] [Indexed: 11/30/2022]
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18
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Mora-Montes HM, Ponce-Noyola P, Villagómez-Castro JC, Gow NA, Flores-Carreón A, López-Romero E. Protein glycosylation in Candida. Future Microbiol 2010; 4:1167-83. [PMID: 19895219 DOI: 10.2217/fmb.09.88] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Candidiasis is a significant cause of invasive human mycosis with associated mortality rates that are equivalent to, or worse than, those cited for most cases of bacterial septicemia. As a result, considerable efforts are being made to understand how the fungus invades host cells and to identify new targets for fungal chemotherapy. This has led to an increasing interest in Candida glycobiology, with an emphasis on the identification of enzymes essential for glycoprotein and adhesion metabolism, and the role of N- and O-linked glycans in host recognition and virulence. Here, we refer to studies dealing with the identification and characterization of enzymes such as dolichol phosphate mannose synthase, dolichol phosphate glucose synthase and processing glycosidases and synthesis, structure and recognition of mannans and discuss recent findings in the context of Candida albicans pathogenesis.
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19
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Alpha-glucosidase promotes hemozoin formation in a blood-sucking bug: an evolutionary history. PLoS One 2009; 4:e6966. [PMID: 19742319 PMCID: PMC2734994 DOI: 10.1371/journal.pone.0006966] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Accepted: 07/17/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Hematophagous insects digest large amounts of host hemoglobin and release heme inside their guts. In Rhodnius prolixus, hemoglobin-derived heme is detoxified by biomineralization, forming hemozoin (Hz). Recently, the involvement of the R. prolixus perimicrovillar membranes in Hz formation was demonstrated. METHODOLOGY/PRINCIPAL FINDINGS Hz formation activity of an alpha-glucosidase was investigated. Hz formation was inhibited by specific alpha-glucosidase inhibitors. Moreover, Hz formation was sensitive to inhibition by Diethypyrocarbonate, suggesting a critical role of histidine residues in enzyme activity. Additionally, a polyclonal antibody raised against a phytophagous insect alpha-glucosidase was able to inhibit Hz formation. The alpha-glucosidase inhibitors have had no effects when used 10 h after the start of reaction, suggesting that alpha-glucosidase should act in the nucleation step of Hz formation. Hz formation was seen to be dependent on the substrate-binding site of enzyme, in a way that maltose, an enzyme substrate, blocks such activity. dsRNA, constructed using the sequence of alpha-glucosidase gene, was injected into R. prolixus females' hemocoel. Gene silencing was accomplished by reduction of both alpha-glucosidase and Hz formation activities. Insects were fed on plasma or hemin-enriched plasma and gene expression and activity of alpha-glucosidase were higher in the plasma plus hemin-fed insects. The deduced amino acid sequence of alpha-glucosidase shows a high similarity to the insect alpha-glucosidases, with critical histidine and aspartic residues conserved among the enzymes. CONCLUSIONS/SIGNIFICANCE Herein the Hz formation is shown to be associated to an alpha-glucosidase, the biochemical marker from Hemipteran perimicrovillar membranes. Usually, these enzymes catalyze the hydrolysis of glycosidic bond. The results strongly suggest that alpha-glucosidase is responsible for Hz nucleation in the R. prolixus midgut, indicating that the plasticity of this enzyme may play an important role in conferring fitness to hemipteran hematophagy, for instance.
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20
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Kurakata Y, Uechi A, Yoshida H, Kamitori S, Sakano Y, Nishikawa A, Tonozuka T. Structural insights into the substrate specificity and function of Escherichia coli K12 YgjK, a glucosidase belonging to the glycoside hydrolase family 63. J Mol Biol 2008; 381:116-28. [PMID: 18586271 DOI: 10.1016/j.jmb.2008.05.061] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 05/16/2008] [Accepted: 05/21/2008] [Indexed: 10/22/2022]
Abstract
Proteins belonging to the glycoside hydrolase family 63 (GH63) are found in bacteria, archaea, and eukaryotes. Eukaryotic GH63 proteins are processing *-glucosidase I enzymes that hydrolyze an oligosaccharide precursor of eukaryotic N-linked glycoproteins. In contrast, the functions of the bacterial and archaeal GH63 proteins are unclear. Here we determined the crystal structure of a bacterial GH63 enzyme, Escherichia coli K12 YgjK, at 1.78 A resolution and investigated some properties of the enzyme. YgjK consists of the N-domain and the A-domain, joined by a linker region. The N-domain is composed of 18 antiparallel beta-strands and is classified as a super-beta-sandwich. The A-domain contains 16 *-helices, 12 of which form an (*/*)(6)-barrel; the remaining 4 *-helices are found in an extra structural unit that we designated as the A'-region. YgjK, a member of the glycoside hydrolase clan GH-G, shares structural similarity with glucoamylase (GH15) and chitobiose phosphorylase (GH94) [corrected] both of which belong to clan GH-L or GH-L-like [corrected] In crystal structures of YgjK in complex with glucose, mannose, and galactose, all of the glucose, mannose, and galactose units were located in the catalytic cleft. YgjK showed the highest activity for the *-1,3-glucosidic linkage of nigerose, but also hydrolyzed trehalose, kojibiose, and maltooligosaccharides from maltose to maltoheptaose, although the activities were low. These findings suggest that YgjK is a glucosidase with relaxed specificity for sugars.
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Affiliation(s)
- Yuma Kurakata
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-Cho, Fuchu, Tokyo 183-8509, Japan
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21
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Faridmoayer A, Scaman CH. Truncations and functional carboxylic acid residues of yeast processing alpha-glucosidase I. Glycoconj J 2007; 24:429-37. [PMID: 17458696 DOI: 10.1007/s10719-007-9035-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 02/25/2007] [Accepted: 04/04/2007] [Indexed: 11/24/2022]
Abstract
Yeast alpha-glucosidase I (Cwh41p) encoded by CWH41 is an endoplasmic reticulum (ER) membrane-bound glycoprotein (833 residues), which plays an important role in the early steps of the N-glycosylation pathway. In this study functional expression of three truncated fragments of Cwh41p, all containing the catalytic region, was investigated. Cwht1p (E35-F833), with deletion of the N-terminus and transmembrane domain, was expressed as a catalytically active fragment while R320-F833(Cwht2p) and M526-F833 (Cwht3p) were not detected. Significantly higher glucosidase I activity was found in a soluble extract from yeast overexpressing CWHT1 (1,400 U/g biomass) than yeast overexpressing CWH41 (300 U/g biomass). Cwht1p was purified as a soluble 94 kDa non-glycosylated protein with a specific activity (3,600 U/mg protein) comparable to that of the soluble alpha-glucosidase I (3000 U/mg protein). These findings indicate that the active conformation of the enzyme is not dependent on protein glycosylation and suggest that the M1-I28 region of Cwh41p carries an ER-targeting signal sequence. In addition, two highly conserved carboxylic acid residues, E580 and D584 of Cwht1p (corresponding to E613 and D617 of Cwh41p), located within the catalytic domain of yeast enzyme were subjected to mutation. Substitution of each residue with Ala resulted in low expression and undetectable glucosidase I activity. These findings indicate that E613 and D617 play a crucial role in maintaining alpha-glucosidase I activity.
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Affiliation(s)
- Amirreza Faridmoayer
- Food, Nutrition, and Health Program, University of British Columbia, Vancouver, V6T 1Z4, Canada
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22
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Faridmoayer A, Scaman CH. Binding residues and catalytic domain of soluble Saccharomyces cerevisiae processing alpha-glucosidase I. Glycobiology 2005; 15:1341-8. [PMID: 16014748 DOI: 10.1093/glycob/cwj009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Alpha-glucosidase I initiates the trimming of newly assembled N-linked glycoproteins in the lumen of the endoplasmic reticulum (ER). Site-specific chemical modification of the soluble alpha-glucosidase I from yeast using diethylpyrocarbonate (DEPC) and tetranitromethane (TNM) revealed that histidine and tyrosine are involved in the catalytic activity of the enzyme, as these residues could be protected from modification using the inhibitor deoxynojirimycin. Deoxynojirimycin could not prevent inactivation of enzyme treated with N-bromosuccinimide (NBS) used to modify tryptophan residues. Therefore, the binding mechanism of yeast enzyme contains different amino acid residues compared to its mammalian counterpart. Catalytically active polypeptides were isolated from endogenous proteolysis and controlled trypsin hydrolysis of the enzyme. A 37-kDa nonglycosylated polypeptide was isolated as the smallest active fragment from both digests, using affinity chromatography with inhibitor-based resins (N-methyl-N-59-carboxypentyl- and N-59-carboxypentyl-deoxynojirimycin). N-terminal sequencing confirmed that the catalytic domain of the enzyme is located at the C-terminus. The hydrolysis sites were between Arg(521) and Thr(522) for endogenous proteolysis and residues Lys(524) and Phe(525) for the trypsin-generated peptide. This 37-kDa polypeptide is 1.9 times more active than the 98-kDa protein when assayed with the synthetic trisaccharide, alpha-D-Glc1,2alpha-D-Glc1,3alpha-D-Glc-O(CH2)(8)COOCH(3), and is not glycosylated. Identification of this relatively small fragment with catalytic activity will allow mechanistic studies to focus on this critical region and raises interesting questions about the relationship between the catalytic region and the remaining polypeptide.
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Affiliation(s)
- Amirreza Faridmoayer
- Food, Nutrition, and Health, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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23
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Ishimizu T, Sasaki A, Okutani S, Maeda M, Yamagishi M, Hase S. Endo-beta-mannosidase, a plant enzyme acting on N-glycan: purification, molecular cloning, and characterization. J Biol Chem 2004; 279:38555-62. [PMID: 15247239 DOI: 10.1074/jbc.m406886200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endo-beta-mannosidase is a novel endoglycosidase that hydrolyzes the Manbeta1-4GlcNAc linkage in the trimannosyl core structure of N-glycans. This enzyme was partially purified and characterized in a previous report (Sasaki, A., Yamagishi, M., Mega, T., Norioka, S., Natsuka, S., and Hase, S. (1999) J. Biochem. 125, 363-367). Here we report the purification and molecular cloning of endo-beta-mannosidase. The enzyme purified from lily flowers gave a single band on native-PAGE and three bands on SDS-PAGE with molecular masses of 42, 31, and 28 kDa. Amino acid sequence information from these three polypeptides allowed the cloning of a homologous gene, AtEBM, from Arabidopsis thaliana. AtEBM was engineered for expression in Escherichia coli, and the recombinant protein comprised a single polypeptide chain with a molecular mass of 112 kDa corresponding to the sum of molecular masses of three polypeptides of the lily enzyme. The recombinant protein hydrolyzed pyridylamino derivatives (PA) of Manalpha1-6Manbeta1-4Glc-NAcbeta1-4GlcNAc into Manalpha1-6Man and GlcNAcbeta1-4Glc-NAc-PA, showing that AtEBM is an endo-beta-mannosidase. AtEBM hydrolyzed Man(n)Manalpha1-6Manbeta1-4GlcNAcbeta1-4GlcNAc-PA (n = 0-2) but not PA-sugar chains containing Manalpha1-3Manbeta or Xylosebeta1-2Manbeta as for the lily endo-beta-mannosidase. AtEBM belonged to the clan GH-A of glycosyl hydrolases. Site-directed mutagenesis experiments revealed that two glutamic acid residues (Glu-464 and Glu-549) conserved in this clan were critical for enzyme activity. The amino acid sequence of AtEBM has distinct differences from those of the bacterial, fungal, and animal exo-type beta-mannosidases. Indeed, AtEBM-like genes are only found in plants, indicating that endo-beta-mannosidase is a plant-specific enzyme. The role of this enzyme in the processing and/or degradation of N-glycan will be discussed.
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Affiliation(s)
- Takeshi Ishimizu
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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24
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Faridmoayer A, Scaman CH. An improved purification procedure for soluble processing alpha-glucosidase I from Saccharomyces cerevisiae overexpressing CWH41. Protein Expr Purif 2004; 33:11-8. [PMID: 14680956 DOI: 10.1016/j.pep.2003.09.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2003] [Revised: 06/29/2003] [Indexed: 11/30/2022]
Abstract
Processing alpha-glucosidase I, which is encoded by CWH41, regulates one of the key steps in asparagine-linked glycoprotein biosynthesis by cleaving the terminal alpha-1,2-linked glucose from Glc(3)Man(9)GlcNAc(2), the common oligosaccharide precursor. This cleavage is essential for further processing of the oligosaccharide to the complex, hybrid, and high mannose type carbohydrate structures found in eukaryotes. A method is described for the purification of the soluble form of the alpha-glucosidase I, from recombinant Saccharomyces cerevisiae overexpressing CWH41. A homogeneous enzyme preparation was obtained in higher yield than previously reported. Cultivation of recombinant S. cerevisiae in a fermenter increased the biomass 1.7 times per liter and enzyme production 2 times per liter compared to cultivation in shake flasks. Ammonium sulfate precipitation with three chromatography steps, including chromatography on an N-(5'-carboxypentyl)-1-deoxynojirimycin column, resulted in highly purified enzyme with no detectable contamination by other alpha- and beta-aryl-glycosidases. The purification procedure reproducibly yielded 40 microg of pure enzyme per gram wet biomass. Enzyme that was purified using an alternative procedure contained minor impurities and was hydrolyzed by an endogenous proteolytic activity to peptides that retained full catalytic activity. Controlled trypsin hydrolysis of the highly purified enzyme released polypeptide(s) containing the alpha-glucosidase I catalytic domain, with no loss of catalytic activity. This suggests that the catalytic domain of yeast alpha-glucosidase I is resistant to trypsin hydrolysis and remains fully functional after cleavage.
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Affiliation(s)
- Amirreza Faridmoayer
- Department of Food, Nutrition, and Health, University of British Columbia, 6650 NW Marine Drive, Vancouver, BC, Canada V6T 1Z4
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25
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Bravo-Torres JC, Villagómez-Castro JC, Calvo-Méndez C, Flores-Carreón A, López-Romero E. Purification and biochemical characterisation of a membrane-bound α-glucosidase from the parasite Entamoeba histolytica. Int J Parasitol 2004; 34:455-62. [PMID: 15013735 DOI: 10.1016/j.ijpara.2003.11.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2003] [Revised: 10/22/2003] [Accepted: 11/05/2003] [Indexed: 10/26/2022]
Abstract
An alpha-glucosidase was solubilised from a mixed membrane fraction of Entamoeba histolytica and purified to homogeneity by a two-step procedure consisting of ion exchange chromatography in a Mono Q column and affinity chromatography in concanavalin A-sepharose. Although the enzyme failed to bind the lectin, this step rendered a homogenous and more stable enzyme preparation that resolved into a single polypeptide of 55 kDa after SDS-PAGE. As measured with 4-methylumbelliferyl-alpha-D-glucopyranoside (MUalphaGlc) as substrate, glycosidase activity was optimum at pH 6.5 with different buffers and at 45 degrees C. Although the enzyme preferentially hydrolysed nigerose (alpha1,3-linked), it also cleaved kojibiose (alpha1,2-linked), which was the second preferred substrate, and to a lesser extent maltose (alpha1,4), trehalose (alpha1,1) and isomaltose (alpha1,6). Activity on alpha1,3- and alpha1,2-linked disaccharides was strongly inhibited by the glycoprotein processing inhibitors 1-deoxynojirimycin and castanospermine but was unaffected by australine. Glucose and particularly 3-deoxy-D-glucose and 6-deoxy-D-glucose were strong inhibitors of activity, whereas 2-deoxy-D-glucose and other monosaccharides had no effect. Enzyme activity on MUalphaGlc was very sensitive to inhibition by diethylpyrocarbonate suggesting a critical role of histidine residues in enzyme catalysis. Other amino acid modifying reagents such as N-ethylmaleimide and N-(3-dimethylaminopropyl)-N'ethylcarbodiimide showed a moderate effect or none at all, respectively. Results are discussed in terms of the possible involvement of this glycosidase in N-glycan processing.
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Affiliation(s)
- José C Bravo-Torres
- Facultad de Química, Instituto de Investigación en Biología Experimental, Universidad de Guanajuato, Apartado Postal No 187, Guanajuato, Gto 36000, México
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Current awareness on yeast. Yeast 2002; 19:1183-90. [PMID: 12371408 DOI: 10.1002/yea.828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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